One lucky little girl is about to wake up with a tiny white kitten on Christmas Day, and the best part are the the baby's gorgeous differently-colored eyes!

Six-year-olds Hannah and Lyla are both survivors of a rare and aggressive childhood eye cancer called retinoblastoma.

Sectoral (or partial) heterochromia: Here, a single eye displays multiple shades. Part of the iris may be a different color than the rest. For example, a green iris with a hazel patch.

Others have a colored sector (like Bosworth) or will have central heterochromia, which is basically a ring of extra color between the pupil and the iris. “Central is pretty common,” says Schwab.

Van Morrison waxed poetic about a brown-eyed girl, while Eric Clapton sang about a woman who “made my blue eyes blue.” Eye color is a distinct part of your features, unique to you.

And, speaking of eyes, the right-hander’s are two different colors. His left eye is brown and his right is blue.